/*
 * <copyright>
 *  
 *  Copyright 1997-2007 BBNT Solutions, LLC
 *  under sponsorship of the Defense Advanced Research Projects
 *  Agency (DARPA).
 * 
 *  You can redistribute this software and/or modify it under the
 *  terms of the Cougaar Open Source License as published on the
 *  Cougaar Open Source Website (www.cougaar.org).
 * 
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *  
 * </copyright>
 */
/*
         NaturalOrderComparator.java -- Perform 'natural order' comparisons of strings in Java.
         Copyright (C) 2003 by Pierre-Luc Paour <natorder@paour.com>

         Based on the C version by Martin Pool, of which this is more or less a straight conversion.
         Copyright (C) 2000 by Martin Pool <mbp@humbug.org.au>

         This software is provided 'as-is', without any express or implied
         warranty.  In no event will the authors be held liable for any damages
         arising from the use of this software.

         Permission is granted to anyone to use this software for any purpose,
         including commercial applications, and to alter it and redistribute it
         freely, subject to the following restrictions:

         1. The origin of this software must not be misrepresented; you must not
         claim that you wrote the original software. If you use this software
         in a product, an acknowledgment in the product documentation would be
         appreciated but is not required.
         2. Altered source versions must be plainly marked as such, and must not be
         misrepresented as being the original software.
         3. This notice may not be removed or altered from any source distribution.
 */
package org.cougaar.util;

// CHANGES:
//   set package to "org.cougaar.util"
//   replaced "import java.util.*" with explicit imports,
//   added "main" file reader support

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

/**
 * A sorting comparator to sort strings numerically,
 * ie [1, 2, 10], as opposed to [1, 10, 2].
 */
public final class NaturalOrderComparator implements  Comparator {

	public static final Comparator NUMERICAL_ORDER = new NaturalOrderComparator();

	private NaturalOrderComparator() {
		// no-arg constructor
	}

	int compareRight(String a, String b) {
		int bias = 0;
		int ia = 0;
		int ib = 0;

		// The longest run of digits wins.  That aside, the greatest
		// value wins, but we can't know that it will until we've scanned
		// both numbers to know that they have the same magnitude, so we
		// remember it in BIAS.
		for (;; ia++, ib++) {
			char ca = charAt(a, ia);
			char cb = charAt(b, ib);

			if (!Character.isDigit(ca) && !Character.isDigit(cb)) {
				return bias;
			} else if (!Character.isDigit(ca)) {
				return -1;
			} else if (!Character.isDigit(cb)) {
				return +1;
			} else if (ca < cb) {
				if (bias == 0) {
					bias = -1;
				}
			} else if (ca > cb) {
				if (bias == 0)
					bias = +1;
			} else if (ca == 0 && cb == 0) {
				return bias;
			}
		}
	}

	public int compare(Object o1, Object o2) {
		String a = o1.toString();
		String b = o2.toString();

		int ia = 0, ib = 0;
		int nza = 0, nzb = 0;
		char ca, cb;
		int result;

		while (true) {
			// only count the number of zeroes leading the last number compared
			nza = nzb = 0;

			ca = charAt(a, ia);
			cb = charAt(b, ib);

			// skip over leading spaces or zeros
			while (Character.isSpaceChar(ca) || ca == '0') {
				if (ca == '0') {
					nza++;
				} else {
					// only count consecutive zeroes
					nza = 0;
				}

				ca = charAt(a, ++ia);
			}

			while (Character.isSpaceChar(cb) || cb == '0') {
				if (cb == '0') {
					nzb++;
				} else {
					// only count consecutive zeroes
					nzb = 0;
				}

				cb = charAt(b, ++ib);
			}

			// process run of digits
			if (Character.isDigit(ca) && Character.isDigit(cb)) {
				if ((result = compareRight(a.substring(ia), b
						.substring(ib))) != 0) {
					return result;
				}
			}

			if (ca == 0 && cb == 0) {
				// The strings compare the same.  Perhaps the caller
				// will want to call strcmp to break the tie.
				return nza - nzb;
			}

			if (ca < cb) {
				return -1;
			} else if (ca > cb) {
				return +1;
			}

			++ia;
			++ib;
		}
	}

	static char charAt(String s, int i) {
		if (i >= s.length()) {
			return 0;
		} else {
			return s.charAt(i);
		}
	}

	public static void main(String[] args) {
		String[] strings;
		if (args.length > 0) {
			String filename = args[0];
			try {
				List data = new ArrayList();
				BufferedReader br = new BufferedReader(new FileReader(
						filename));
				while (true) {
					String line = br.readLine();
					if (line == null)
						break;
					int sep = line.indexOf("#");
					if (sep >= 0) {
						line = line.substring(0, sep);
					}
					line = line.trim();
					if (line.length() == 0)
						continue;
					data.add(line);
				}
				br.close();
				strings = (String[]) data.toArray(new String[data
				                                             .size()]);
			} catch (Exception e) {
				System.err.println("Unable to read " + filename);
				e.printStackTrace();
				System.exit(-1);
				return;
			}
		} else {
			strings = new String[] { "1-2", "1-02", "1-20", "10-20",
					"fred", "jane", "pic01", "pic2", "pic02", "pic02a",
					"pic3", "pic4", "pic 4 else", "pic 5", "pic05",
					"pic 5", "pic 5 something", "pic 6", "pic   7",
					"pic100", "pic100a", "pic120", "pic121",
					"pic02000", "tom", "x2-g8", "x2-y7", "x2-y08",
			"x8-y8" };
		}

		List orig = Arrays.asList(strings);

		System.out.println("Original: " + orig);

		List scrambled = Arrays.asList(strings);
		Collections.shuffle(scrambled);

		System.out.println("Scrambled: " + scrambled);

		Collections.sort(scrambled,
				NaturalOrderComparator.NUMERICAL_ORDER);

		System.out.println("Sorted: " + scrambled);
	}
}